Pollution and contermination is major problem for water purity in most countries, and industrial activities is the main cause of this problem. A state in my country known as Rivers state suffers from this problem more than any other part of the country as a result of oil exploration carried out by Shell and other oil companies in the state. Their water and land are killed with oil spillage making unsafe for drinking. They suffer so much as a result that.
In my area which is known as Ganges Basin (I live in the Himalayan area in India) which has number of rivers and other water sources has been worst affected due to industrial disposal right in to the rivers besides boring reverse wells which dispose off waste in the earth in place of arranging treatment of waste. Even the slaughter houses are doing the same which causes even the blood of animals mixing with drinking water.